1. Field
This disclosure relates to memory modules for use in computers and other applications.
2. Description of the Related Art
Random access memory devices are widely used for working memory in computers and other electronics devices. Static random access memory (SRAM) devices will store data for as long as electrical power is applied to the memory device. Dynamic random access memory (DRAM) memory devices provide large memory capacity than SRAM devices, but the data stored in DRAM devices must be periodically refreshed. Synchronous dynamic random access memory (SDRAM) devices load commands and data based on a clock signal, which allows the memory devices to be synchronized with a computer bus. Double data rate SDRAM devices (DDR SDRAM) load and output data on both the rising and falling edges of the clock signal such that the data rate is double the clock rate. Current generation DDR3 SDRAM devices are operable at clock rates of up to 800 MHz.
Random access memory devices are commonly packaged on dual inline memory modules, or DIMMs, which may be plugged into mating connectors on a computer motherboard. Memory devices and DIMMs are generally designed in accordance with specifications published by the Joint Electron Device Engineering Council (JEDEC). JEDEC is the semiconductor engineering standardization body of the Electronic Industries (EIA), a trade association that represents all areas of the electronic industries in the United States.
Throughout this description, elements appearing in figures are assigned three-digit reference designators, where the most significant digit is the figure number and the two least significant digits are specific to the element. An element that is not described in conjunction with a figure may be presumed to have the same characteristics and function as a previously-described element having a reference designator with the same least significant digits.